Loose Wet avalanches occur when water is running through the snow pack, and release at or below the trigger point. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or if we were to have a rain-on-snow event.
Most of the loose wet activity we have seen has been fairly small point releases, but could turn into a bad situation if you were to be caught in the moving wet debris and pushed into trees or off a cliff. However, the wet slab avalanche that was observed yesterday on a south facing aspect up Lick Creek is a much more powerful beast and deserves respect. This is due to the fact that they are harder to forecast when they will avalanche and if they do avalanche they can become large and entrain more snow and debris as they flow. Fortunately this was only observed on one aspect in one isolated area, but keep an eye out.
Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.
We have been tracking two persistent weak layers in the top three feet of our snow pack. One is buried deeply and was blanketed by the MLK storm cycle, the other near the surface. The warm temps and direct sun light is making the layer closer to the surface hard to find. The deeper buried layer is not as easily affected by sun and warm temps and remains intact on north facing slopes that are protected from direct solar radiation. This is the same layer that is the cause of the fatal avalanche on January 31st. A persistent weak layer such as this is a low probably, but HIGH CONSEQUENCE scenario.
Triggering a slab due to this weak layer is becoming more difficult, but I would not let my guard down. Take the time to carefully assess terrain choices on the north half of the compass today. Especially areas where the snow cover is thinner which allows the buried surface hoar to be closer to the surface, and in turn more reactive.
The Friends of the Payette Avalanche Center (FPAC) is vital to the operation of the Payette Avalanche Center, and they need your support!
This Saturday at the Little Ski Hill from 6-9 ish. Some of the goods: Beer from McCall's own SRB, Waverunner rental from Cheap Thrills, Jug Mountain Ranch Mountain Bike Shuttles and skis from Dynafit! Practice up with those beacons and get ready for some timed beacon races with great prizes. Family Friendly environment with night skiing, BBQ and plenty of parking available on both sides of the highway. Thanks to all the donors that have supported us in the past and again this year! Kids are FREE at the door(does not include night skiing).
PAC forecasters were up Lick Creek yesterday and conditions were as forecasted. Sun and a lack of a hard freeze overnight Tuesday made for warm snow on all solar aspects. We saw a good deal of loose wet slides near rocks and steep slopes, and even saw evidence of a wet slab avalanche on a due south facing aspect. We were able to find cool snow on a north facing aspect, however, we also found buried graupel (55 cm down from snow surface) and buried surface hoar (110cm down).
It was another warm night in the high country with temps hovering around freezing at 7,600 feet and getting all the way down to a bone chilling 20 at Brundage Reservoir (but is already back to 33 as of 6:30 am). We should see an increase in cloud cover today with a slight chance of isolated showers this afternoon into this evening. This is due to the strong upper level ridge that has been over us this week slowly shifting to the east of McCall. Tonight into next week expect to see a more active weather pattern return to the area as a series of storms moves in from the northwest.
This avalanche advisory is provided through a partnership between the Payette National Forest and the Payette Avalanche Center. This advisory covers the West Central Mountains between Hard Butte on the north and Council Mountain on the south. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires at midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.